1. Field of the Invention
The present invention relates to a slide rail for permitting a sliding movement of an automotive seat in the foreward and backward directions and adjustment thereof.
2. Description of Prior Art
Particularly, a wobbling or rattling is easy to occur in such construction of slide rail wherein an upper rail of an inverted U-shaped configuration in section is slidably fitted within a lower rail, the upper rail being fixed to a seat and the lower rail being fixed to a floor of the automobile. This is because a load or external force is applied to the slide rail in a direction transversely thereof, resulting in the upper rail being deformed relative to the lower one.
To solve this problem, there has been proposed a slide rail as shown in FIG. 1, which is constructed in the abovementioned manner, with a roller (30') being provided in the inverted U-shaped part of the upper rail (1'). The roller (30') is, therefore, effective in preventing the upper rail (1') against deformation. Designation (6') denotes balls disposed between the upper and lower rails (1')(2') for facilitating a slidability of the upper rail (1') with respect to the lower one (2').
However, such prior art has been found defective in its locking mechanism (4'). As shown, the locking mechanism (4') comprises a lock hole (21') perforated in the bottom of the lower rail (2'), a lock plate (41') having a lock pawl (41'a) to be engaged into the lock hole (21'), and a control spindle (42') fixed to the lock plate (41'). The control spindle (42') extends along the longitudinal direction of the lower rail (2') in parallel therewith, and is rotatably supported by a bracket (43') fixed to the standing part of the upper rail (1'). Thus, by rotating the control spindle (42'), the lock pawl (41'a) of the lock plate (41') is disengaged from or into the lock hole (21'), to thereby unlock or lock the upper rail (1') to the lower one (2'). But, if a great load is exerted upon the upper rail (1'), making effort to forcibly slide it along the lower rail (2'), the lock pawl (41'a) or the mating lock hole (21') is easily deformed or damaged, because of their simple interconnection.